above standard air." Implementation of the Clean Air Act Amendments of 1970-Part I, Hearings, 92d Cong., 2d Sess. 12 (1972). Senator Thomas Eagleton, the vicechairman of the subcommittee who presided over the hearings, replied (id. at 14-15):

I don't agree with you when you say that nondegradation is not a part of the 1970 Clean Air Amendments. I think it very much is.

Section 101 (b), subsection 1, reads as follows: "The purposes of this title are, No. 1, to protect and enhance the quality of the Nation's air resources so as to promote the public health and welfare and the productive capacity of its population." That is language that is similar to, almost identical to, language that exists in the Water Pollution Control Act and also similar to language that existed in the previous 1967 Air Quality Act which was taken to mean nondegradation, and that policy was frequently discussed in the deliberations on this bill.

HEW itself under the 1967 Air Quality Act talks of nondegradation in this way:

"In addition it was indicated earlier in this chapter that the explicit purpose of this Act is to protect and enhance the quality of the Nation's air resources."

Protect and enhance again. Former Secretary of HEW Finch described the aforesaid language as meaning nondegradation and that was the policy he intended to pursue.

So I think nondegradation was in the 1970 law, very much is in the 1970 law, and has to be part of the implementation plan submitted by a State.

Mr. Ayres replied that he was "being an overcautious attorney, I am afraid. I stand corrected." Id. at 15. Subsequently, Senator Eagleton again stated that "the statute requires nondegradation." Id. at 18. He quoted

ILT

in support of this proposition the language of the Senate Report on the 1970 Act (S. Rep. No. 1196, 91st Cong., 2d Sess. 11 (1970)), which specifically forbids deterioration. Hearings, pp. 20-21. When Senator Eagleton repeated his belief that non-degradation "was written into the law as passed by the Congress," Professor William H. Rodgers of the University of Washington Law School agreed. Id. at 141-142.

Benjamin Wake, the Administrator of the Division of Environmental Sciences of the Montana State Department of Health and Environmental Sciences, characterized the position of EPA at the hearings as (id. at 178):

The thrust of this whole philosophy is that the Nation must become uniformly dirty. I would suppose in places such as Chicago and New York or Gary, Ind., perhaps, where the air quality is consistently worse than the standards, that to be as dirty as the air quality standards would be an improvement. In Montana to be as dirty as the air quality standards is to acknowledge that existing air quality must become worse. He stated that "the need to preserve air quality is just as great as the need to roll back *." Id. at 179.

*

*

The Administrator of EPA defended his position at the hearings that the Clean Air Act did not prohibit significant deterioration of air quality. Id. at 246-247, 249, 271276. His principal arguments were that he did not understand what non-degradation meant and that, if Congress wanted such a standard, it should write it specifically into the Act. Senator Baker supported the Administrator's position (id. at 275), while Senator Eagleton repeatedly stated that the Administrator was ignoring the clear language and intent of the statute (id. at 246-249, 271276).

This legislative and administrative history demonstrates that 42 U.S.C. 1857 (b) (1) does not permit the Administrator to approve state plans which allow significant deterioration of the air. This position is supported by the legislative history of the Air Quality Act of 1967. It was stated specifically in the guidelines adopted by HEW under that Act. It was clearly stated, to both Houses of the Congress, as the proper interpretation of the 1967 and 1970 Acts by the Secretary and Under Secretary of HEW who then had the responsibility to enforce air-pollution legislation. It was stated in the House and Senate Reports and other portions of the legislative history of the 1970 Clean Air Act. It has been clearly stated since 1970 by the leadership of the responsible subcommittees in Congress. It was even adopted by the Administrator of EPA in the national ambient air-quality standards.

In short, the legislative history is overwhelming. While, as we will see below (pp. 39-48), petitioner attempts to distinguish some of the statements on which we rely, the fact is that every passage in the legislative history specifically considering either the meaning of 42 U.S.C. 1857 (b) (1) or whether significant deterioration is permitted by the statute supports respondents' construction of the statute. Not a single sentence of legislative history directly supports petitioner. And, more broadly, it is clear that Congress intended "to authorize a massive attack on air pollution." S. Rep. No. 1196, 91st Cong., 2d Sess. 1 (1970). 40 C.F.R. 51.12 (b), which allows an increase of air pollution over most of the country and a total increase of air pollution, is hardly consistent with this intent.

The administrative history also supports respondents. "When faced with a problem of statutory construction, this Court shows great deference to the interpretation given the statute by the officers or agency charged with its administration." Udall v. Tallman, 380 U.S. 1, 16 (1965). Accord, e.g., Rosado v. Wyman, 397 U.S. 397,

415 (1970); Zuber v. Allen, 396 U.S. 168, 192 (1969). This principle clearly applies in this case to the Administrator's interpretation prior to 1971 rather than the Administrator's belated change of position.

First, an administrative interpretation of a statute is entitled to special weight when it is adopted soon after passage of the statute. E.g., Zuber v. Allen, supra, 396 U.S. at 192; Udall v. Tallman, supra, 380 U.S. at 16. "Particularly is this respect due when the administrative practice at stake ‘involves a contemporaneous construction of a statute by the men charged with the responsibility of setting its machinery in motion; of making the parts work efficiently and smoothly while they are untried and new.' "Power Reactor Development Co. v. International Union of Electricians, 367 U.S. 396, 408 (1961); accord, United States v. Zucca, 351 U.S. 91, 96 (1956); United States v. American Trucking Ass'ns, 310 U.S. 534, 549 (1940); Nitrogen Products Co. v. United States, 288 U.S. 294, 315. Here, the contemporaneous administrative interpretation of 42 U.S.C. 1857 (b), soon after its passage in the Air Quality Act of 1967, was that it prohibited significant deterioration.

Second, this Court has held that the (Zuber v. Allen, supra, 396 U.S. at 192):

impact [of an administrative interpretation] carries most weight when the administrators participated in drafting and directly made known their views to Congress in Committee hearings. * ** In these circumstances, absent any indication that Congress differed with the responsible department, a court should resolve any ambiguity in favor of the administrative construction, if such construction enhances the general purpose and policies underlying the legislation. Accord, Power Reactor Development Co. v. International Union of Electricians, supra, 367 U.S. at 408-409. Here, the Administration bill was a major source of the 1970

amendments to the Act and the interpretation of the responsible departments were conveyed to both houses of Congress by Secretaries Finch and Veneman. Instead of any indication that Congress disagreed, the legislative history shows agreement with the administrative position. Thus, the administrative interpretation of the statute prior to 1971, that it prohibits significant deterioration of air quality, is entitled to particularly great weight.

In contrast petitioner's belated interpretation of the Act in 1971 is not entitled to significant consideration. It is obviously not "established" (United States v. Public Utilities Commission, 315 U.S. 295, 315 (1953)), "longstanding" (United States v. Republic Steel Corp., 362 U.S. 482, 490, note 5 (1970)), or "consistent" (Burnet v. Chicago Portrait Co., 285 U.S. 1, 16 (1932)). Instead of being acquiesced in by Congress (see, e.g., Zuber v. Allen, supra, 396 U.S. at 192), it has been expressly and forcefully disapproved by leaders of both the Senate and House committees. This Court has stated in Skidmore v. Swift & Co., 323 U.S. 134, 140 (1944):

We consider that the rulings, interpretations and opinions of the Administrator under the Act, while not controlling upon the courts by reason of their authority, do constitute a body of experience and informed judgment to which courts and litigants may properly resort for guidance. The weight of such a judgment in a particular case will depend upon the thoroughness evident in its consideration, the validity of its reasoning, its consistency with earlier and later pronouncements, and all those factors which give it power to persuade, if lacking power to control.

Applying this test, petitioner's 1971 decision to overrule the consistent administrative interpretation of the statute without giving any reason or legal justification is not entitled to weight. Thus, the administrative interpretation of the Act, taken as a whole, strongly supports the lan